JP5969874B2 - Pneumatic tire manufacturing method - Google Patents

Description

The present invention relates to a manufacturing method of the pneumatic tire and facilitate removal from the tire stiffness core after vulcanization forming.

  In recent years, a tire forming method using a rigid core (hereinafter referred to as “core method”) has been proposed in order to improve the formation accuracy of the tire (see, for example, Patent Documents 1 and 2). The rigid core has, on the outer surface, a tire molding surface having a contour shape equal to the tire lumen surface of the vulcanized tire, and on this tire molding surface, an inner liner rubber, a carcass ply, a belt ply, a sidewall rubber, A raw tire is formed by sequentially pasting unvulcanized tire components such as tread rubber. The green tire is inserted into the vulcanization mold together with the rigid core, and is thereby sandwiched between the rigid core as the inner mold and the vulcanization mold as the outer mold so that the green tire is vulcanized. Molded.

  On the other hand, in the core method, it is necessary to take out the rigid core from the tire after vulcanization molding. Therefore, as shown in FIG. 8A, the core body a is formed of a plurality of core segments b divided in the circumferential direction. Specifically, the core segment b includes first and second core segments b1 and b2 that are alternately arranged in the circumferential direction, and the first core segment b1 has both end surfaces in the circumferential direction. It inclines in the direction in which the circumferential width decreases toward the inside in the radial direction. The second core segment b2 has both end surfaces in the circumferential direction inclined in a direction in which the circumferential width increases inward in the radial direction.

  Accordingly, the core segment b can be moved radially inward one by one from the second core segment b2, and by this movement, the second core segment b2 is sequentially taken out from the bead portion of the tire. It becomes possible.

  However, at the time of vulcanization molding, as shown in FIG. 8B, the core body a and the tire t are in close contact with each other. Therefore, when the core segment b is pulled inward in the radial direction, it is difficult to easily remove the core segment b from the tire t, and it takes a lot of time to remove the core body a from the tire t. Become. In particular, it is difficult to peel off the first core segment b.

  In addition, it is proposed that a release agent is applied to the surface of the core body a to improve the peelability of the core body a from the tire t. However, in this case, it becomes difficult to attach the tire constituent member to the surface of the core main body a at the time of forming the raw tire, resulting in a reduction in the formation efficiency and formation accuracy of the raw tire.

JP 2011-131526 A JP 2011-161896 A

Therefore, the present invention is based on forming a concave groove at a predetermined angle at a predetermined position on the tire molding surface in at least one second core segment, and between the tire after vulcanization molding and the core segment. It is an object of the present invention to provide a method for manufacturing a pneumatic tire that can be easily peeled off without using a release agent and can improve the detachability of the core body from the tire.

In order to solve the above problems, the invention of claim 1 of the present application is a method for manufacturing a pneumatic tire using a rigid core having an annular core body provided with a tire molding surface on the outer surface,
A raw tire forming step of forming a raw tire by sequentially affixing unvulcanized tire components on the tire molding surface, and the raw tire together with a rigid core is placed in a vulcanization mold for vulcanization. And a vulcanization process to form,
The core body is composed of a plurality of core segments divided in the circumferential direction,
In addition, the core segment includes a first core segment in which both end faces in the circumferential direction are inclined in a direction in which the circumferential width decreases toward the inside in the radial direction, and both end faces in the circumferential direction are directed in the radially inward direction. Inclined in the direction in which the direction width increases, and composed of second core segments arranged alternately with the first core segments,
Around the tire molding surface of at least one second core segment from the vicinity of the radially inner end position of the tire molding surface to the vicinity of the maximum core width position where the tire molding surface protrudes most outward in the tire axial direction. A concave groove extending at an angle of 45 to 90 ° with respect to the direction is formed.

  According to a second aspect of the present invention, the groove has a groove depth Hg of 1.0 mm or less and a groove width Wg on the tire molding surface of 5.0 mm or less.

  According to a third aspect of the present invention, in the cross section of the concave groove, the upper corner where the groove wall and the tire molding surface intersect, and the lower corner where the groove wall and the groove bottom intersect with each other are formed by an arc surface, It is characterized by a radius of 0.5 mm or more.

  As described above, according to the present invention, the tire molding surface of the core segment extends at an angle of 45 to 90 ° with respect to the circumferential direction from the vicinity of the radially inner end position of the tire molding surface to the vicinity of the maximum core width position. A concave groove is formed. This concave groove functions as an air passage when the core segment is pulled out inward in the radial direction, and helps to create an air layer at the interface between the core segment and the tire. As a result, the releasability between the core segment and the tire is improved, and the workability of removing the core body from the tire can be improved. In addition, the said effect is exhibited effectively because the said groove is formed in the core segment pulled out initially. Therefore, the concave groove only needs to be formed in at least one second core segment. However, it is more preferably formed in each second core segment, and further preferably formed in each first and second core segment.

It is sectional drawing explaining the green tire formation process in the manufacturing method of the pneumatic tire of this invention. It is sectional drawing explaining a vulcanization | cure process. It is a side view which shows a core main body. It is a disassembled perspective view which shows a rigid core. It is sectional drawing orthogonal to the length direction of a ditch | groove. (A)-(C) are perspective views of the member material which forms a tire structural member. (A), (B) is explanatory drawing of the formation method of a carcass ply, (C), (D) is explanatory drawing of the formation method of a belt ply. (A), (B) is explanatory drawing of the removal method of the core main body from a tire.

Hereinafter, embodiments of the present invention will be described in detail.
The method for manufacturing a pneumatic tire according to the present invention includes a raw tire forming step K1 using a rigid core 10 and a vulcanizing step K2. As shown in FIG. 1, the rigid core 10 includes an annular core body 11 having a tire molding surface S on its outer surface. In the raw tire formation step K1, the rigid core 10 is unvulcanized on the tire molding surface S. The raw tire 6 is formed by affixing the tire constituent members T sequentially.

FIG. 1 shows an example of a green tire 6 formed by the green tire forming step K1. This raw tire 6 is, in this example,
(A) One or more sheets from the tread portion 6a to the side wall portion 6b to the bead portion 6c, in this example, one carcass ply T1,
(A) One or more, in this example, two belt plies T2, arranged radially outside the carcass ply T1 and inside the tread portion 6a,
(C) One or more sheets arranged in the radially outer side of the belt ply T2, one band ply T3 in this example,
(D) Tread rubber T4 forming the outer surface of the tread portion 6a,
(E) a sidewall rubber T5 forming the outer surface of the sidewall portion 6b;
(F) Chafer rubber T6 for preventing rim displacement that forms the outer surface of the bead portion 6c;
(G) Inner liner rubber T7 that forms the inner surface of the tire.
(H) Inner and outer bead cores T8, T9 and (K) each of the inner and outer bead cores T8, which are arranged in the bead portion 6c and sandwich the inner end in the radial direction of the carcass ply T1 from inside and outside in the tire axial direction. Internal and external bead apex rubbers T10, T11 for reinforcing beads that rise from T9, respectively
It is formed from a plurality of tire constituent members T.

  The carcass ply T1 includes a carcass cord arranged at an angle of, for example, 90 ° with respect to the tire equator Co, and a topping rubber that covers the carcass cord. The belt ply T2 has, for example, a belt cord arranged at an angle θ of 10 to 40 ° (shown in FIG. 7D) with respect to the tire equator Co, and a topping rubber covering the belt cord. The band ply T3 includes a band cord arranged in the tire circumferential direction and a topping rubber covering the band cord.

  Among these tire constituent members T, the rubber members which are the tread rubber T4, the sidewall rubber T5, the chafer rubber T6, the inner liner rubber T7, the bead apex rubbers T10 and T11 are as shown in FIG. 6A in this example. Further, it is formed by a so-called strip winding method (STW method) in which a long tape-shaped rubber strip 8 is spirally wound. The rubber composition and the cross-sectional dimension of the rubber strip 8 are set for each tire constituent member T.

  Among the tire constituent members T, the cord plies that are the carcass ply T1, the belt ply T2, and the band ply T3 are formed using a cord strip 9 shown in FIG. 6B. The cord strip 9 has a long tape shape in which an array of tire cords 9a aligned in the length direction is covered with a topping rubber 9b. In the case of the carcass ply T1, as shown in FIGS. 7A and 7B, a strip 9A obtained by cutting the cord strip 9 with a predetermined length is arranged so that the tire cord 9a is perpendicular to the tire equator Co. In this direction, it is formed by sticking sequentially in the tire circumferential direction. Further, in the case of the belt ply T2, as shown in FIGS. 7C and 7D, a strip 9B obtained by obliquely cutting the cord strip 9 with a predetermined length is connected to the tire equator Co. It is formed by sticking sequentially in the tire circumferential direction in a direction inclined at the angle θ. The band ply T3 is formed by continuously winding the cord strip 9 spirally in the tire circumferential direction. The material, thickness, distance between cords, rubber composition of the topping rubber 9b, and the like of the tire cord 9a in the cord strip 9 are set for each tire constituent member T.

  Of the tire component T, the inner and outer bead cores T8 and T9 are formed by winding the rubberized wire 7 shown in FIG. 6C spirally from the inner side to the outer side in the radial direction.

  In the vulcanization step K2, as shown schematically in FIG. 2, the raw tire 6 and the rigid core 10 are put into the vulcanization mold 2 and vulcanized.

  The raw tire forming step K1 and the vulcanizing step K2 are not limited to this, and various conventional raw tire forming steps and vulcanizing steps using the rigid core 10 can be suitably employed. .

  Next, the rigid core 10 used in the present invention includes at least a core body 11 having a tire molding surface S on the outer surface, as shown in FIGS. In this example, the rigid core 10 is arranged on both sides of the core body 11, the cylindrical core 12 inserted into the center hole 11 h of the core body 11, and the core body 11 in the axial direction. The case where a pair of side plates 13 and 13 are provided is shown.

  The tire molding surface S has a contour shape equal to the tire lumen surface of the vulcanized tire, and is formed of a tread molding surface portion Sa, a sidewall molding surface Sb, and a bead molding surface Sc. 3 and 4, the core body 11 includes a plurality of core segments 14 that are divided in the circumferential direction. The core segments 14 are alternately arranged in the circumferential direction. 2 core segments 14A and 14B. In the first core segment 14A, both end surfaces in the circumferential direction are inclined in such a direction that the circumferential width decreases inward in the radial direction. Further, the second core segment 14B is inclined such that both circumferential end surfaces thereof increase in the circumferential width toward the inside in the radial direction.

  Accordingly, the core body 11 can move inward in the radial direction one by one from the second core segment 14B as in the prior art, and this movement causes the tires to move in order one by one from the second core segment 14B. It can be taken out from the bead part.

  At this time, in order to facilitate the peeling of the core segment 14 from the tire and to improve the workability of removing the core body 11 from the tire, at least the groove segment is formed in the tire molding surface S of the core segment 14B that is first taken out. 20 is formed. That is, the concave groove 20 is formed in the tire molding surface S of at least one second core segment 14B. In this example, as shown in FIGS. 1 and 3, the most preferable case is shown in which the groove 20 is formed in the tire molding surface S of each core segment 14.

  The concave groove 20 extends from the vicinity of the radially inner end position P1 of the tire molding surface S to the vicinity of the maximum core width position P2 at an angle α of 45 to 90 ° with respect to the circumferential direction. The core maximum width position P2 is a position where the tire molding surface S protrudes most outward in the tire axial direction, and “near” the core maximum width position P2 is from the core maximum width position P2. Means a region having a radial distance of 10 mm or less. Further, “near” the radial inner end position P1 means a region having a radial distance from the radial inner end position P1 of 10 mm or less.

  Such a concave groove 20 functions as an air passage when the core segment 14 is moved radially inward, and helps to form an air layer at the interface between the core segment 14 and the tire. As a result, the releasability between the core segment 14 and the tire is improved, and the workability of removing the core body 11 from the tire can be improved.

  When the angle α of the concave groove 20 is less than 45 °, the fitting force between the concave groove 20 and the ridge protrusion on the tire side made of rubber filled therein becomes a large resistance, and the core This tends to lower the workability of removing the main body 11. Therefore, the angle α is 45 ° or more, preferably 60 ° or more, more preferably 75 ° or more.

  When the radially inner end 20L of the concave groove 20 is located radially inward of the inner end position P1, rubber flows into a portion beyond the inner end position P1 and spew is generated. When the distance from the inner end position P1 exceeds 10 mm, the spew becomes excessive, resulting in a disadvantage in the airtightness after the rim assembly. Conversely, when the inner end 20L of the concave groove 20 is located radially outward from the inner end position P1 and the distance from the inner end position P1 exceeds 10 mm, the core segment 14 and the tire Air becomes difficult to enter during this period, and the peelability is lowered. For these reasons, the inner and outer distances of the inner end 20L of the concave groove 20 from the inner end position P1 are each 10 mm or less, preferably 5 mm or less, more preferably 3 mm or less.

  Further, when the radially outer end 20U of the concave groove 20 is positioned radially inward from the core maximum width position P2 and the distance from the core maximum width position P2 exceeds 10 mm, the core segment Air becomes difficult to enter between the tire 14 and the tire, and the peelability is lowered. Further, even if the outer end 20U of the concave groove 20 exceeds the core maximum width position P2 radially outward, no further improvement in peelability is expected. However, as a result of the surface area of the tire molding surface S being reduced, the adhesive force between the tire molding surface S and the tire constituent member T at the time of forming the raw tire tends to be reduced. As a result, in particular, when the inner liner rubber T7 is formed by winding the rubber strip 8, the adhesion with the rubber strip 8 becomes insufficient, causing a disadvantage in the formation efficiency and formation accuracy of the raw tire. In addition, the amount of rubber (corresponding to the ridge protrusion on the tire side) filled in the concave groove 20 is disadvantageous to the tire mass and material cost. For these reasons, the inner and outer distances of the outer end 20U of the concave groove 20 from the core maximum width position P2 are each 10 mm or less, preferably 5 mm or less, more preferably 3 mm or less.

  In addition, as shown in FIG. 5, the groove depth Hg of the concave groove 20 is preferably 1.0 mm or less, and the groove width Wg on the tire molding surface S is preferably 5.0 mm. When the groove depth Hg exceeds 1.0 mm and when the groove width Wg exceeds 5.0 mm, the amount of rubber filled in the concave groove 20 increases unnecessarily. Incurs a cost penalty. Further, when the groove width Wg exceeds 5.0 mm, the surface area of the tire molding surface S is reduced and the adhesiveness with the tire constituent member T is lowered.

  Even if the groove depth Hg is too small or the groove width Wg is too small, it becomes difficult for air to enter between the core segment 14 and the tire, and it becomes difficult to sufficiently improve the peelability. Accordingly, the lower limit value of the groove depth Hg is preferably 0.3 mm or more, and the lower limit value of the groove width Wg is preferably 1.0 mm or more.

  As shown in FIG. 5, in the cross section of the groove 20, the upper corner U where the groove wall 20a and the tire molding surface S intersect, and the lower corner L where the groove wall 20a and the groove bottom 20b intersect, The arc surface 21 is preferably formed, and the radius R of the arc surface 21 is particularly preferably 0.5 mm or more. As a result, the cross section of the ridge protrusion on the tire side made of rubber filled in the concave groove 20 becomes smooth. As a result, it is possible to suppress the occurrence of cracks and the like starting from the protrusions.

  In addition, the said groove | channel 20 is formed in the core segment 14 pulled out initially, and the said effect is exhibited effectively. Accordingly, the concave groove only needs to be formed in at least one second core segment 14B. However, it is more preferably formed in each second core segment 14B, and further preferably formed in each first and second core segment 4A, 4B. Further, the number of the concave grooves 20 formed is one or more for one core segment 14, and the upper limit thereof is 36 or less, and further 12 or less from the viewpoint of adhesiveness with the tire constituent member T. preferable. Further, when a plurality of concave grooves 20 are formed, the concave grooves 20 can be crossed.

  Moreover, in the rigid core 10 of this example, as shown in FIG. 4, dovetail grooves extending in the axial direction of the core and engaging with each other on the outer peripheral surface of the core 12 and the inner peripheral surface of the core segment 14. One or the other of 15a and ant tenon 15b is formed. Thereby, the core 12 and each core segment 14 are connected so that relative movement is possible only in the axial direction. A side plate 13 is fixed to one end of the core 12 in the axial direction, and a side plate 13 is detachably attached to the other end. The core 12 prevents the core segments 14 from moving inward in the radial direction, and the side plates 13 on both sides prevent the core segments 14 from moving in the axial direction.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

  In order to confirm the effect of the present invention, a tire forming rigid core 10 having a structure shown in FIGS. 3 and 4 and having a tire size of 205 / 55R16 was prototyped according to the specifications shown in Table 1, and each rigid core 10 was The tire was manufactured using this. And the working time at the time of taking out the core main body 11 from a vulcanized tire was compared after the vulcanization molding.

  Each of the rigid cores 10 has substantially the same specifications except for the groove 20. The concave grooves 20 are formed on the side surfaces on both sides of the core segment 14. In each of the recessed grooves 20, the radially inner end 20L of the recessed groove 20 is located at the radially inner end position P1 of the tire molding surface S, and the radially outer end 20U of the recessed groove 20 is at the core maximum width position P2. positioned. The upper corner and the lower corner of the concave groove 20 are each formed by a circular arc surface 21 having a radius of 5 mm.

  As shown in Table 1, it was confirmed that the rigid core 10 of the example has improved releasability due to the formation of the concave groove 20 and can significantly reduce the time for taking out the core body 11 from the tire.

6 Raw tire 10 Rigid core 11 Core body 14A, 14B, 14 Core segment 20 Concave groove 20a Groove wall 20b Arc surface K1 Raw tire formation process K2 Vulcanization process L Lower corner P1 Inner end position P2 Maximum core width position S Tire molding surface T Tire component U Upper corner

Claims (3)

A method for manufacturing a pneumatic tire using a rigid core having an annular core body provided with a tire molding surface on an outer surface,
A raw tire forming step of forming a raw tire by sequentially affixing unvulcanized tire components on the tire molding surface, and the raw tire together with a rigid core is placed in a vulcanization mold for vulcanization. And a vulcanization process to form,
The core body is composed of a plurality of core segments divided in the circumferential direction,
In addition, the core segment includes a first core segment in which both end faces in the circumferential direction are inclined in a direction in which the circumferential width decreases toward the inside in the radial direction, and both end faces in the circumferential direction are directed in the radially inward direction. Inclined in the direction in which the direction width increases, and composed of second core segments arranged alternately with the first core segments,
Around the tire molding surface of at least one second core segment from the vicinity of the radially inner end position of the tire molding surface to the vicinity of the maximum core width position where the tire molding surface protrudes most outward in the tire axial direction. A method for manufacturing a pneumatic tire, wherein a concave groove extending at an angle of 45 to 90 ° with respect to the direction is formed.   The method for producing a pneumatic tire, wherein the groove has a groove depth Hg of 1.0 mm or less and a groove width Wg on a tire molding surface of 5.0 mm or less. In the cross section of the concave groove, the upper corner where the groove wall and the tire molding surface intersect, and the lower corner where the groove wall and the groove bottom intersect with each other are formed by an arc surface, and the radius of the arc surface is 0.5 mm or more. The manufacturing method of the pneumatic tire of Claim 1 characterized by the above-mentioned.

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